JP6115047B2 - Thermoelectric conversion module and manufacturing method thereof - Google Patents

Description

  The present invention relates to a thermoelectric conversion module having improved bonding reliability between a thermoelectric conversion element and an electrode, and a method for manufacturing the same.

  The thermoelectric conversion module that converts thermal energy into electrical energy using the Seebeck effect has features such as no drive unit, clear structure, and maintenance-free, but because of its low energy conversion efficiency, satellite It has been used only in limited products such as power supplies for industrial use. However, in order to realize an environmentally harmonious society, attention has been paid as a method of recovering waste heat as thermal energy, and development to related products such as incinerators, industrial furnaces, and automobiles is being studied. Against this background, thermoelectric conversion modules are desired to have improved durability, improved conversion efficiency, and reduced cost.

  However, the thermoelectric conversion modules currently in practical use are mainly bismuth-tellurium systems as described in Patent Document 1, for example, and the operating temperature range is limited to a low temperature of 300 ° C. or lower. Therefore, when the thermoelectric conversion module is applied to the above-mentioned industrial furnace, automobile, etc., thermoelectric conversion elements such as silicon-germanium system, magnesium silicide system, manganese silicide system and the like that can operate at higher temperature than bismuth-tellurium system are required. Become.

  In many cases, the bismuth-tellurium thermoelectric conversion element and the electrode are joined together by a soft brazing material such as solder. When high-temperature thermoelectric conversion elements such as those described above are joined with a soft brazing material, the joining reliability between the thermoelectric conversion element and the electrode is lowered by melting and flowing out the soft brazing material under the usage environment of the thermoelectric conversion module. Is concerned. For this reason, when the soft brazing material is used, the use environment temperature of the thermoelectric conversion module is limited.

  On the other hand, Patent Document 1 discloses a group consisting of Al, Mg, and Ti between a part of a bismuth-tellurium-based or lead-tellurium-based P-type or N-type thermoelectric conversion element and a Cu electrode. By providing an intervening layer that is one of them or an alloy of them, and using a highly heat-resistant brazing filler, the heat resistance of the thermoelectric conversion module is increased and Cu of the electrode material is prevented from diffusing to the element side. And joining.

  On the other hand, in Patent Document 2, in order to eliminate the problems caused by using a soft brazing material, the electrode material and the thermoelectric conversion element are made of hard brazing material through an intervening layer whose thermoelectric conversion element end is made of Ag. A bonded thermoelectric conversion module is described.

  Patent Document 3 discloses a thin film layer mainly composed of Al between the P-type cobalt-antimony thermoelectric conversion element and the electrode member and between the N-type cobalt-antimony thermoelectric conversion element and the electrode member. Are formed and bonded to each other.

  Further, Patent Document 4 discloses a P-type thermoelectric conversion element and an N-type thermoelectric conversion element made of a magnesium silicide-based alloy, respectively, a titanium or titanium alloy layer, or a titanium or titanium alloy layer and an aluminum or aluminum alloy layer as an intermediate layer. Is described as being sandwiched between and joined to an electrode.

  The thermoelectric conversion module can convert heat into electricity by giving a temperature difference in the thermoelectric conversion element. For this reason, in the joint portion between the thermoelectric conversion element and the electrode, stress is generated in the joint portion due to the difference in the coefficient of linear expansion between the thermoelectric conversion element and the electrode in an operating environment, and there is a concern that the joint portion or the thermoelectric conversion element may be broken. The stress generated in this way becomes higher as the use environment temperature is higher, or as the difference in linear expansion coefficient between the thermoelectric conversion element, the bonding material, and the electrode is larger. In particular, a thermoelectric conversion module that is assumed to be used in an environment of 300 ° C. or higher is a big problem.

  In Patent Document 5, p-type and n-type thermoelectric conversion elements are connected to Mo electrodes using carbon and Ni brazing, and thermal stress generated due to a temperature difference is formed by joining each thermoelectric conversion element with oxide glass. A line-type thermoelectric conversion module that relaxes the above is described.

  Further, in Patent Document 6, a required number of substantially L-type n-type semiconductor materials and p-type semiconductor materials are alternately combined, and hot or cold compression molding is performed using different metal materials on the high temperature side and the low temperature side. A thermoelectric conversion element having a plurality of pn junctions in a connecting direction is described by pn junction by powder metallurgy.

JP-A-9-293906 JP 2005-317834 A JP 2003-304006 A JP 2006-49736 A Japanese Patent No. 3469811 JP 2001-189497 A

In joining the thermoelectric conversion element and the electrode as described above, there are the following problems.
(1) Solder joint
In the case of lead-free solder, which is currently the mainstream, the melting point of the solder is approximately 220-230 ° C, and even in high-temperature lead-free solder, the melting point is 400 ° C or less, and there is a possibility of remelting in the usage environment. high.
(2) Joining with brazing filler metal
The brazing filler metal has a melting point of approximately 600 to 800 ° C., which is higher than that of the solder material, and can be used as a bonding material in a high temperature environment of 300 ° C. or more. Although there are Ag brazing containing Ag as a main component and Au brazing containing Au as a main component, since the brazing material has a bonding strength of about 5 to 25 MPa, the bonding strength is low. Further, in an atmospheric environment, the deterioration of the joint due to oxidation is remarkable, and there is a concern that the joint reliability may be lowered.
(3) Contact connection by pressurization
Since the connection form of the thermoelectric conversion element and the electrode is contact, there is a concern that the conversion efficiency of the thermoelectric conversion module is lowered due to the contact thermal resistance of the contact interface. Furthermore, in the case of the collective pressurization method, the variation in the applied pressure between the elements becomes the temperature variation for each element, and the characteristics may be deteriorated. Moreover, when the applied pressure is increased in order to reduce the contact thermal resistance, there is a concern about cracks or chipping in the thermoelectric conversion element.
(4) Joining with an intermediate layer in between
Patent Documents 3 and 4 show that a thermoelectric conversion element and an electrode are joined with an Al or Al alloy sandwiched between the thermoelectric conversion element and the electrode. However, in the method described in Patent Document 3, a pressure of 300 kg / cm ^{2 to} 700 kg / cm ² is applied while being heated to 525 ° C. to 575 ° C. at the time of joining, and cracks are generated in the thermoelectric conversion elements and joints. There is a fear. Further, even in the method described in Patent Document 4, a pressure of several tens of MPa is applied while being heated to 600 to 700 ° C. at the time of bonding, which may cause cracks in the thermoelectric conversion element and the bonded portion.

  Furthermore, in the junction part of a thermoelectric conversion element and an electrode, stress generate | occur | produces in a junction part by the linear expansion coefficient difference between a thermoelectric conversion element and an electrode in an operating environment, and there exists a concern about destruction in a junction part or a thermoelectric conversion element. The stress generated in this manner increases as the use environment temperature increases or as the difference in linear expansion coefficient between the thermoelectric conversion element, the bonding material, and the electrode increases. In particular, a thermoelectric conversion module that is assumed to be used in an environment of 300 ° C. or higher is a big problem. In order to solve this problem, Patent Document 5 proposes a strain relaxation structure using carbon and nickel brazing. However, in this connection method, the thermal resistance between the element and the electrode increases, so that the characteristics deteriorate. Since it is a brittle material, there is a concern that it may break in an environment where repeated strain or impact occurs.

  Furthermore, in the invention described in Patent Document 6, it is described that a metal material is used to integrally form by pn bonding by hot or cold compression molding or powder metallurgy. Although not specified in the above, a configuration is disclosed that can solve the problem that stress is generated in the joint due to a difference in linear expansion coefficient. However, Patent Document 6 describes that different metal materials are used on the high temperature side and the low temperature side as the metal material for integrally forming, and does not describe using the same metal material. Moreover, it does not describe what kind of joining state the interface with the integrally formed metal material is made. Furthermore, Patent Document 6 does not describe a configuration in which heat is transferred on a high temperature side and a low temperature side of an integrally formed thermoelectric conversion element.

  The present invention provides a thermoelectric conversion module capable of ensuring high reliability even in a high temperature environment or in an environment where thermal stress is generated due to a temperature cycle and efficiently transmitting the outer peripheral temperature to the thermoelectric conversion element. Is.

In order to solve the above problems, in the present invention, a method for manufacturing a thermoelectric conversion module includes a plurality of p-type thermoelectric conversion elements containing silicon and a plurality of n-type thermoelectric conversion elements containing silicon. Are arranged with the high-temperature side surface and the low-temperature side surface arranged alternately, and aluminum is formed at the junction between the plurality of alternately arranged p-type thermoelectric conversion elements and the plurality of n-type thermoelectric conversion elements. Of a thermoelectric conversion element containing silicon in aluminum between the bonding metal material and the p-type thermoelectric conversion element and between the bonding metal material and the n-type thermoelectric conversion element. Joining in the state in which a plurality of alloy layers that contain components and relax the stress generated in the joint are formed to electrically connect a plurality of p-type thermoelectric conversion elements and a plurality of n-type thermoelectric conversion elements Connected in series and electrically in series The high-temperature side surfaces and the low-temperature side surfaces of the plurality of p-type thermoelectric conversion elements and the plurality of n-type thermoelectric conversion elements connected to each other are covered with an insulating material having good thermal conductivity.

  A feature of the present invention is that a p-type thermoelectric conversion element and an n-type thermoelectric conversion element are directly joined to form a structure that eliminates an electrode, and thus occurs between a thermoelectric element and an electrode under a high temperature environment or a temperature fluctuation environment. It is possible to suppress thermal stress and ensure high reliability even in an actual use environment. In addition, by connecting the electrodeless thermoelectric conversion element assembly and the outer case in contact with each other, it is possible to suppress the generation of stress due to a difference in linear expansion coefficient between the electrodeless thermoelectric conversion element assembly and the case. Furthermore, since the heat of the case can be transmitted to the thermoelectric conversion element without using an electrode, the efficiency can be improved.

It is the side view which extracted the element vicinity of the thermoelectric conversion module in the 1st Example of this invention. It is a flowchart which shows the flow of a process of manufacture of the electrodeless thermoelectric conversion element assembly in a 1st Example of this invention. It is a flowchart which shows the flow of the process of case sealing of the thermoelectric conversion module in the 1st Example of this invention. It is a perspective view of the state where the upper case of the thermoelectric conversion module concerning a first embodiment of the present invention was removed. It is a perspective view of the state where the upper case of the thermoelectric conversion module concerning a first embodiment of the present invention was mounted. It is a flowchart which shows the flow of a process of manufacture of the electrodeless thermoelectric conversion element assembly in the 2nd Example of this invention. It is the side view which extracted the element vicinity of the thermoelectric conversion module in the 3rd Example of this invention.

  In the present invention, the p-type thermoelectric conversion element of the thermoelectric conversion module is not configured to connect the p-type thermoelectric conversion element and the n-type thermoelectric conversion element using the conventional electrode material, but without using the electrode material (electrodeless). An alloy layer made of a bonding metal is formed between the n-type thermoelectric conversion element and a direct electrical connection.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a side view of the vicinity of an element of a thermoelectric conversion module 500 in the first embodiment of the present invention. Reference numeral 10 denotes a bonding material, 11 denotes a p-type thermoelectric conversion element, 12 denotes an n-type thermoelectric conversion element, 13 denotes a high thermal conductive insulating material, and 14 denotes an outer case. The bonding material 10 is preferably aluminum, nickel, tin, copper, zinc, germanium, magnesium, gold, silver, indium, lead, bismuth, tellurium, or an alloy containing any one of these metals as a main component. The upper surface side bonding material 10 and the lower surface side bonding material 10 may be made of the same material or different materials. The p-type thermoelectric conversion element 11 and the n-type thermoelectric conversion element 12 (hereinafter collectively referred to as the thermoelectric conversion element 100) are silicon-germanium-based, iron-silicon-based, bismuth-tellurium-based, magnesium-silicon-based. , Lead-tellurium-based, cobalt-antimony-based, bismuth-antimony-based, Heusler alloy-based, half-Heusler alloy-based material, and the like.

  In the following examples, the p-type thermoelectric conversion element 11 is composed of silicon and germanium powder containing impurities such as boron, aluminum, gallium and the like that give the characteristics of a p-type semiconductor, and the n-type thermoelectric conversion element 12 is A silicon-germanium thermoelectric conversion element obtained by sintering silicon-germanium powder containing impurities of 1% or less, such as phosphorus and antimony, imparting the characteristics of an n-type semiconductor, respectively, by a pulse discharge method or a hot press method will be described.

  The high thermal conductive insulating material 13 is an insulating material with good thermal conductivity, and includes a thermoelectric conversion element 100 such as a resin material such as epoxy or urethane containing a material with good thermal conductivity such as metal or carbon, or thermal conductive grease. A material having good thermal conductivity that is not chemically and metallicly bonded to the substrate is preferable. Further, the high thermal conductive insulating material 13 is an anisotropic high thermal conductive insulating material having anisotropy having a high thermal conductivity in the direction perpendicular to the outer case 14 and the thermoelectric conversion element 100 and a low thermal conductivity in the horizontal direction. The material may have a high strength in the thickness direction but a low strength in the horizontal direction and can be easily sheared.

  The material of the outer case 14 is preferably a material having a high thermal conductivity mainly composed of metal, ceramic, carbon or the like. In the following description, the outer case 14 is described as a metal case.

  In the following embodiments, the bonding material 10 is either aluminum or an aluminum alloy foil containing silicon, germanium or the like in aluminum, or a foil made of powder containing aluminum, silicon, germanium or the like in aluminum or aluminum. The case where is used will be described.

  As shown in FIG. 1, the p-type thermoelectric conversion element 11 and the n-type thermoelectric conversion element 12 are alternately joined by the joining material 10 at the upper end and the lower end. Further, the high heat conductive insulating material 13 and the thermoelectric conversion element 100 are contact-connected, and the outer case 14 is pressurized from above and below with screws, hermetically sealed vacuum packaging, or the high heat conductive insulating material 13 is attached. The shape is maintained by adhering with adhesive force. Moreover, the outer peripheral case 14 and the high thermal conductive insulating material 13 may be connected or may be in contact or bonded, and the form is not limited. When the integrated outer case in which the high thermal conductive insulating material 13 is formed on the outer case 14 in advance by coating, bonding, molding, casting, plating, vapor deposition, etc., the heat of the outside air is efficiently transmitted to the thermoelectric conversion element 100. Can do.

  The thermoelectric conversion module is a module that generates an electromotive force according to the temperature difference by giving a temperature difference to both ends of the thermoelectric conversion element 100. The case where the upper surface of FIG. 1 is made high temperature and the lower surface is made low temperature is shown below.

  A current flows through the thermoelectric conversion element 100 due to the temperature difference applied to the upper and lower surfaces. The current flows from the high temperature side to the low temperature side (in FIG. 1, from top to bottom) in the p-type thermoelectric conversion element 11, and from the low temperature side to the high temperature side (in FIG. 1, from bottom to top) in the n-type thermoelectric conversion element 12. The downstream side of each thermoelectric conversion element 100 is joined to the upstream side of the adjacent thermoelectric conversion element 100 using the bonding material 10 to form an electrical series path. The electrodeless thermoelectric conversion element assembly 1 is configured by joining a plurality of the thermoelectric conversion elements 100 connected in series in this manner in a planar shape, a line shape, or the like. In the configuration shown in FIG. 1, the electrodeless thermoelectric conversion element assembly 1 is shown as a configuration in which a plurality of thermoelectric conversion elements 100 form one electrical series path, but the present invention is not limited to this. Instead, the electrodeless thermoelectric conversion element assembly 1 may be configured in a state in which a plurality of electrical series paths formed by the plurality of thermoelectric conversion elements 100 are provided and connected in parallel.

  If the thermoelectric conversion element 100 is joined to the outer case 14 or the high thermal conductive insulating material 13 (for example, metal bonding) when the high temperature side becomes 300 ° C. or higher in an actual use environment, the difference in linear expansion coefficient of each member Stress and strain are generated in the vicinity of the joint, and there is a concern that the joint may break or peel off and the thermoelectric conversion element 100 may crack. However, in the structure in the present embodiment, since the thermoelectric conversion element 100 and the high thermal conductive insulating material 13 are not a structure fixed with a bonding material but a contact connection, the interface slips to reduce stress and strain. be able to. In addition, when an anisotropic material that is easily deformable in the shear direction is used for the high thermal conductive insulating material 13, the contact interface slips and the anisotropic material is also deformed, so that the effect of reducing stress and strain can be exhibited. In addition, when an anisotropic material having a high thermal conductivity in the thickness direction is used for the high thermal conductivity insulating material 13, heat is transferred preferentially in the thickness direction, so that the heat of the outer case 14 is efficiently transmitted to the thermoelectric conversion element 100. be able to. The thickness of the high thermal conductive insulating material 13 is desirably 0.01 mm to 10 mm from the viewpoint of insulation and thermal resistance.

  Furthermore, in this embodiment, since the electrodes for connecting the thermoelectric conversion elements as described in Patent Document 5 are not necessary, the ratio of the thermoelectric conversion elements 100 per unit area in the plane direction can be increased, and the thermoelectric conversion Since the mounting density of conversion elements increases, the amount of power generation per unit area increases. That is, space-saving power generation is possible.

  FIG. 2 is a side view of the vicinity of the element in the first assembly process example of the thermoelectric conversion module 500 in the first embodiment of the present invention. 1 is an electrodeless thermoelectric conversion element assembly, 11 is a p-type thermoelectric conversion element, 12 is an n-type thermoelectric conversion element, 15 and 16 are metal foils, 20 is a jig for supporting a sample, 21 and 23 are protrusions, and 22 is an upper part This is a joining jig. In this assembly process, the metal foils 15 and 16 will be described as aluminum or an aluminum alloy foil containing silicon, germanium, or the like in aluminum, or a foil made of powder containing silicon, germanium, or the like in aluminum or aluminum.

  The sample support jig 20 may be any material that does not melt in the joining process, such as ceramic or metal. However, in the case of a material that reacts with the metal foils 15 and 16, the metal foil 15 is placed on the surface of the sample support jig 20. , 16 is formed, or a layer that does not react is formed, or a material (such as ceramic) that inhibits or does not react is interposed between the sample supporting jig 20 and the metal foils 15 and 16.

  Hereinafter, the flow of the assembly method of the electrodeless thermoelectric conversion element assembly 1 of FIG. 2 will be described with reference to (a) to (d).

  First, as shown in FIG. 2A, the metal foil 15 is placed on the sample support jig 20 having the protrusions 21 (S201). The protrusion 21 is formed at least under any boundary except the boundary where the p-type thermoelectric conversion element 11 and the n-type thermoelectric conversion element 12 are joined. It is desirable that the height of the protrusions 21 is at least half of the thickness of the metal foil 15. The thickness of the metal foil 15 is preferably 1 to 500 μm. After the metal foil 15 is installed, the thermoelectric conversion element 100 is aligned by avoiding the protrusion 21 of the sample support jig 20 (S202), and the thermoelectric conversion element 100 is placed on the sample support jig 20 with the metal foil 15 sandwiched therebetween. Install (S203). The thermoelectric conversion element 100 may be installed in a lump using a jig (not shown) or may be individually installed, and the method is not limited. In this state, the adjacent thermoelectric conversion elements 100 are spaced apart by the width of the protrusion 21 of the sample support jig 20.

  Next, as shown in FIG. 2 (b), the metal foil 16 is placed on the thermoelectric conversion element 100 installed (S204), and the upper joining jig 22 having the protrusions 23 is installed on the sample supporting jig 20. The alignment is performed on the thermoelectric conversion element 100 (S205). The protrusion 23 of the upper joining jig 22 is formed at least under any boundary except the boundary where the p-type thermoelectric conversion element 11 and the n-type thermoelectric conversion element 12 are joined. It is desirable that the height of the protrusions 21 is at least half of the thickness of the metal foil 16. The thickness of the metal foil 16 is preferably 1 to 500 μm. After the alignment, the upper joining jig 22 is pressurized by setting the load applied to the thermoelectric conversion element 100 to 0.12 kPa or more with the metal foil 16 in between (S206).

  Next, as shown in FIG. 2C, the sample supporting jig 20 and the upper joining jig 22 are heated by a heating means (not shown) in a pressurized state (S207), and the metal foil 15 , 16 are raised to a melting temperature (660 ° C. in the case of aluminum) or higher, and the metal foils 15 and 16 exceeding the melting temperature are melted (S208). On the molten metal foils 15 and 16, the protrusions 21 and 23 serve as dikes, and the p-type thermoelectric conversion element 11 where the protrusions 21 and 23 do not exist and the interfaces 211 and 231 between the n-type thermoelectric conversion element 12 are formed. Molten metal foil flows in and inter-element connection members 151 and 161 (inter-element connection members 151 and 161 are collectively referred to as a bonding material 10 (see FIG. 1)) are formed, and bonding of both thermoelectric conversion elements is realized. To do.

  After a certain period of time has elapsed since the start of heating, heating of the sample support jig 20 and the upper bonding jig 22 is stopped (S209). After that, as shown in FIG. 2 (d), pressurization to the thermoelectric conversion element 100 by the upper bonding jig 22 is stopped and the upper bonding jig 22 is raised (S210), and the thermoelectric conversion element 100 is moved. Is removed from the sample support jig 20, whereby the electrodeless thermoelectric conversion element assembly 1 (an assembly of thermoelectric conversion elements 100 in which a plurality of thermoelectric conversion elements 100 are electrically connected by inter-element connection members 151 or 161) is obtained. It can be formed (S211).

  In the flow described with reference to FIG. 2, the process of joining the upper and lower metal foils 15 and 16 together is shown. However, after joining one of them in advance, the other may be joined. For example, in steps S207 and S208 of FIG. 2, first, the lower sample support jig 20 is heated to melt the metal foil 15 to form the inter-element bonding member 151, and then the whole is inverted and the upper bonding is performed. The upper jig 22 is heated in this state and the metal foil 16 is melted in this state to form the inter-element bonding member 161, as shown in FIG. The electrodeless thermoelectric conversion element assembly 1 may be formed.

Here, the pressure is set to 0.12 kPa or more to prevent the thermoelectric conversion element 100 from being tilted at the time of joining, the thermoelectric conversion element 100 and the sample supporting jig 20, and the thermoelectric conversion element 100 and the upper joining purpose. This is because the molten metal foils 15 and 16 are discharged from the interface of the jig 22 as much as possible, and the adhesion between the thermoelectric conversion element 100, the sample support jig 20, and the upper bonding jig 22 is enhanced. The upper limit of the applied pressure is not particularly limited, but is set to be less than the crushing strength of the element because it is necessary that the element is not destroyed. Specifically, it may be about 1000 MPa or less, but in this embodiment, as described in Patent Documents 3 and 4, a pressure of 300 kg / cm ² or more and 700 kg / cm ² or less is applied at the time of joining, Even without applying a pressure of about 10 MPa, a sufficient effect can be obtained with a pressure of about several MPa.

  The bonding atmosphere may be a non-oxidizing atmosphere. Specifically, a vacuum atmosphere, a nitrogen atmosphere, a nitrogen-hydrogen mixed atmosphere, or the like can be used. When the thermoelectric conversion element 100 is a silicon-germanium element and the metal foils 15 and 16 are aluminum, a layer containing aluminum, silicon, and germanium is formed at the bonding interface between the silicon-germanium element and aluminum. In this layer, a silicon-aluminum layer containing germanium and a silicon-germanium alloy layer containing aluminum of not more than 10% by mass formed by dissolving silicon-germanium constituting the thermoelectric conversion element 100 in aluminum. May be formed. In this case, the interface between the thermoelectric conversion element 100 and the molten metal foils 151 and 161 is a structure composed of a plurality of alloy layers including an alloy layer containing silicon, germanium, and aluminum and an alloy layer mainly containing silicon and germanium. It becomes.

  This alloy layer has high bonding strength and is excellent in oxidation resistance because it contains aluminum, and it is difficult for the bonded portion to deteriorate even in a high temperature environment in the atmosphere. In addition, an alloy containing aluminum, silicon, and germanium is relatively soft, and thus has an action of relieving stress generated at the joint. By these actions, the bonding layer in which an alloy containing aluminum, silicon, and germanium is formed exhibits high bonding reliability over a long period of time. The operation and effect of this bonding layer is as described above, and even if the bonding portion is formed as a multilayer as described above, it can be used without any problem. Note that the upper limit of the bonding temperature is a temperature at which the performance of the thermoelectric conversion element does not deteriorate, specifically, 1000 ° C. or less.

  In the above description, aluminum foil is used as the metal foils 15 and 16, but an aluminum alloy foil containing silicon, germanium or the like in aluminum may be used instead of the aluminum foil. In this case, since the component of the thermoelectric conversion element is contained in aluminum, a eutectic liquid phase is likely to be generated without solid phase diffusion. Further, an aluminum foil and an aluminum alloy foil may be laminated and used.

  Furthermore, instead of the metal foil, aluminum powder or aluminum alloy powder containing silicon, germanium or the like in aluminum may be used. In this case, you may use as a single powder, the layer formed from each powder may be laminated | stacked, and these mixed powders may be used. When such a powder is used, a compact formed by compacting only the powder may be disposed only at a location where the p-type thermoelectric conversion element 11 and the n-type thermoelectric conversion element 12 are joined, or the thermoelectric conversion element 100 in advance. The powder may be applied only to the place where the bonding is performed, and the powder paste formed using a resin or the like may be applied to the portion where the thermoelectric conversion element is bonded. Since the step of installing the foil can be omitted by applying the powder in advance, the manufacturing process can be further simplified.

  As the thermoelectric conversion element 100, other thermoelectric conversion elements such as a magnesium silicide thermoelectric conversion element and a manganese silicide thermoelectric conversion element can also be used. That is, each of these thermoelectric conversion elements contains silicon as a component, and can be joined by the above aluminum and silicon.

  Here, when a magnesium silicide thermoelectric conversion element is used as the thermoelectric conversion element 100, the bonding layer includes a layer structure including an alloy layer containing silicon, magnesium, and aluminum and an alloy layer containing silicon and magnesium as main components. can do.

  In order to obtain such a bonding layer, instead of the aluminum foil or aluminum powder of the above assembly method, an aluminum alloy foil containing silicon, magnesium or the like in aluminum or an aluminum alloy powder containing silicon, magnesium or the like in aluminum is used. It may be used. However, when a magnesium silicide thermoelectric conversion element is used as the thermoelectric conversion element 100, a eutectic phase is generated between aluminum and magnesium at 437 ° C., so the junction temperature is set to 440 ° C. or higher. Further, since magnesium is easily sublimated at a high temperature, the upper limit of the joining temperature is set to 800 ° C. in order to avoid sublimation of magnesium. Other assembly conditions are the same as those shown in FIG.

  In addition, when a manganese silicide thermoelectric conversion element is used as the thermoelectric conversion element 100, the obtained bonding layer has a layer structure including an alloy layer containing silicon, manganese, and aluminum and an alloy layer mainly containing silicon and manganese. It can be. In order to obtain such a bonding layer, instead of the aluminum foil or aluminum powder of the above production method, an aluminum alloy foil containing silicon, manganese or the like in aluminum or an aluminum alloy powder containing silicon, manganese or the like in aluminum is used. It may be used. Each manufacturing condition when a magnesium silicide thermoelectric conversion element is used as the thermoelectric conversion element is the same as that of the silicon-germanium thermoelectric conversion element.

  It is conceivable that, at the joint between the molten metal foils 15 and 16 and the thermoelectric conversion element 100, the reaction is promoted under a manufacturing process or an actual use environment depending on the volume of the metal foil. Therefore, you may form the diffusion prevention layer (reaction suppression layer) previously in the arbitrary locations of the thermoelectric conversion element 100 used as a joining interface. This diffusion prevention layer may be tungsten, titanium, nickel, palladium, molybdenum or the like. This diffusion prevention layer can be formed by plating, vapor deposition, sputtering, thermal spraying, aerosol deposition, or the like.

  FIG. 3 is a flowchart illustrating a method for sealing the electrodeless thermoelectric conversion element assembly 1 in the first embodiment of the present invention to the outer case, and a side view of the thermoelectric conversion module corresponding to each step of the flowchart. It is. 1 is a thermoelectric conversion element assembly, 30 and 32 are outer peripheral cases (corresponding to the outer peripheral case 14 shown in FIG. 1), and 31 and 33 are high thermal conductive insulating materials (corresponding to the high thermal conductive insulating material 13 shown in FIG. 1). is there. The material of the outer casings 30 and 32 is preferably a material having a high thermal conductivity mainly composed of metal, ceramic, carbon or the like. The high thermal conductive insulating materials 31 and 33 are chemically and metallically similar to the thermoelectric conversion element 100 such as those having a thermal conductive material such as metal or carbon in a resin material such as epoxy or urethane, or thermal conductive grease. A material that does not bond to is preferred. In addition, the high thermal conductive insulating materials 31 and 33 are made of an anisotropic material having a high thermal conductivity in the direction perpendicular to the outer casings 30 and 32 and the thermoelectric conversion element and a low thermal conductivity in the horizontal direction. A material that has high strength in the direction but low strength in the horizontal direction and is easy to shear can be used.

  The connection between the outer casings 30 and 32 and the high thermal conductive insulating materials 31 and 33 may be an integrated type in which a high thermal conductive insulating material is formed on the outer casing by molding, casting or the like. Contact connection using pressure, contact connection using pressure without any intervention, contact connection using an internal / external pressure difference in a vacuum sealed package shape, or the like may be used. In FIG. 3, a description will be given in a state in which a high thermal conductive insulating material is formed on the outer case in advance. If a high thermal conductivity material can be formed in advance on the outer case by casting or the like, the contact thermal resistance between the case and the high thermal conductivity insulating material can be suppressed, so that the outside air temperature outside the outer case is transmitted to the thermoelectric conversion element with less temperature loss. be able to.

  As shown in FIG. 3A, the electrodeless thermoelectric conversion element assembly 1 is disposed between the outer peripheral cases 30 and 32 on which the high thermal conductive insulating materials 31 and 33 are formed (S301). At this time, fine alignment is performed by making the areas of the high thermal conductive insulating materials 31 and 33 larger than the horizontal sectional area of the electrodeless thermoelectric conversion element assembly 1 in contact with the high thermal conductive insulating materials 31 and 33. It can be installed without

  After that, as shown in FIG. 3 (b), the electrodeless thermoelectric conversion element assembly 1 is sandwiched between the high heat conductive insulating materials 31 and 33, and is fixed in contact (S302). The thermoelectric conversion module 500 according to the embodiment is completed. FIG. 3 does not show a connection method for fixing the outer peripheral case 30 on the lower surface side and the outer peripheral case 32 on the upper surface side with the electrodeless thermoelectric conversion module 1 sandwiched therebetween. In the electrodeless thermoelectric conversion element assembly 1, any outer peripheral case may be used depending on the application product as long as the outer peripheral case and the thermoelectric conversion element are in contact with each other.

  In the present embodiment, the process of manufacturing the outer peripheral case 32 on the upper surface side and the outer peripheral case 30 on the lower surface side together is shown, but they may be brought into contact with each other.

  As shown in the first embodiment, the p-type thermoelectric conversion element 11 and the n-type thermoelectric conversion element 12 are directly joined to form a structure in which the electrode is eliminated, so that the thermoelectric element can be used in a high temperature environment or a temperature fluctuation environment. The thermal stress generated between the electrodes can be suppressed, and high reliability can be secured even in an actual use environment. In addition, the electrodeless thermoelectric conversion element assembly 1 and the outer casings 30 and 32 are connected to each other, thereby suppressing the generation of stress due to the difference in linear expansion coefficient between the electrodeless thermoelectric conversion element assembly 1 and the outer casings 30 and 32. Furthermore, since the heat of the outer peripheral case 32 can be transferred to the electrodeless thermoelectric conversion element assembly 1 without passing through an electrode, the thermoelectric conversion efficiency can be improved. Moreover, since the mounting density of the thermoelectric conversion elements can be improved, a smaller product with the same performance can be provided.

  FIG. 4 is a perspective view of the thermoelectric conversion module 500 incorporating the electrodeless thermoelectric conversion element assembly 1 according to the first embodiment with the upper case 32 removed. 11 is a p-type thermoelectric conversion element, 12 is an n-type thermoelectric conversion element, 31 is a high heat conductive insulating material (corresponding to the high heat conductive insulating material 13 in FIG. 1), 30 is an outer case (corresponding to the outer case 14 in FIG. 1), Reference numerals 151 and 161 denote inter-element connection members (corresponding to the bonding material 10 shown in FIG. 1). FIG. 4 is a perspective view of the thermoelectric conversion module 500 in the first embodiment described with reference to FIGS. 1 to 3 and shows an electrodeless thermoelectric conversion element assembly 1 in which 64 thermoelectric conversion elements 100 are arranged in a grid pattern. It is. As shown in FIG. 4, the p-type thermoelectric conversion elements 11 and the n-type thermoelectric conversion elements 12 are alternately connected by inter-element connection members 151 or 161 and are electrically connected in series. A lead-out wiring (not shown) is formed from both ends of the series connection, and an electromotive force is taken out to the outside.

  In FIG. 4, the thermoelectric conversion element 100 of the p-type thermoelectric conversion element 11 and the n-type thermoelectric conversion element 12 is represented as a quadrangular prism, but the shape of the thermoelectric conversion element 100 is a quadrangular prism, a triangular prism, a polygonal cylinder, a cylinder, an elliptical cylinder. Or any other columnar shape. Moreover, the area where the thermoelectric conversion element 100 and the high thermal conductive insulating material 31 or 33 are in contact with each other is not necessarily the same, and there may be a difference between one contact area and the other contact area.

  In the configuration shown in FIG. 4, the entire configuration is described as being electrically connected in series. However, this is divided into a plurality of blocks and electrically connected in series in each block. You may comprise so that it may connect in parallel. By configuring the plurality of blocks in parallel as described above, even if a disconnection occurs in one of the plurality of blocks, the electrodeless thermoelectric conversion element assembly can be used if the other blocks are normal. The output from 1 does not become zero, and the risk of the output from the electrodeless thermoelectric conversion element assembly 1 being interrupted can be sufficiently reduced.

  FIG. 5 is a perspective view showing a state where the upper case 32 of the thermoelectric conversion module 500 according to the first embodiment of the present invention is attached. The high heat conductive insulating material 33 and the upper case 32 are covered with the perspective view of FIG. Is. Reference numeral 151 denotes a bonding material, 11 denotes a p-type thermoelectric conversion element, 12 denotes an n-type thermoelectric conversion element, 31 denotes a high thermal conductive insulating material, and 30 denotes an outer peripheral case on the lower surface side. Many thermoelectric conversion elements 100 are in close contact with the inner wall surface of the outer peripheral case 30 on the lower surface side via the high thermal conductive insulating material 31, and are attached to the inner wall surface of the outer peripheral case 32 on the upper surface side via the high thermal conductive insulating material 33. It is in close contact. The outer peripheral case 32 on the upper surface side contacts a heating element (not shown), and the outer peripheral case 30 on the lower surface side is cooled by a cooling means (not shown). Lead wires (not shown) are formed from both ends of the thermoelectric conversion elements 100 connected in series, and the electric power generated in the electrodeless thermoelectric conversion element assembly 1 is output to the outside using the wirings.

  In FIG. 5, the outer peripheral case 32 on the upper surface side and the outer peripheral case 30 on the lower surface side are respectively shown by flat plates, and the connection method between the upper and lower outer peripheral cases 30 and 32 is not shown, but in this embodiment The thermoelectric conversion module 500 can be applied as long as the outer peripheral case 32 on the upper surface side and the outer peripheral case 30 on the lower surface side are in contact with each other via the electrodeless thermoelectric conversion element assembly 1 and the high thermal conductive insulating material 31 or 33, respectively. Any outer case shape may be used depending on the product. Further, the thermoelectric conversion module 500 may have a package structure in which the outer periphery is sealed, and the sealed interior can be selected according to the usage environment such as vacuum, nitrogen filling, air, and argon.

  In this way, by directly joining the p-type thermoelectric conversion element 11 and the n-type thermoelectric conversion element 12 without using an electrode, there is no electrode for connecting the p-type thermoelectric conversion element 11 and the n-type thermoelectric conversion element 12. By adopting such a structure, it is possible to suppress thermal stress generated between the thermoelectric conversion element and the electrode under a high temperature environment or a temperature fluctuation environment, and to ensure high reliability even under an actual use environment. That is, since the p-type thermoelectric conversion element 11 and the n-type thermoelectric conversion element 12 are substantially similar materials, their thermal expansion coefficients are almost the same, and both thermoelectric conversion elements are connected under a high temperature environment or a temperature fluctuation environment. The thermal stress generated in the inter-element connection member 151 or 161 is sufficiently small, and high connection reliability can be ensured.

  In addition, the electrodeless thermoelectric conversion element assembly 1 and the outer casings 30 and 32 are connected to each other, thereby suppressing the generation of stress due to the difference in linear expansion coefficient between the electrodeless thermoelectric conversion element assembly 1 and the outer casings 30 and 32. In addition, since the heat of the case can be transferred to the thermoelectric conversion element without using an electrode, the thermoelectric conversion efficiency can be improved.

  Moreover, since the mounting density of the thermoelectric conversion elements can be improved, a smaller product with the same performance can be provided. Note that some thermoelectric conversion modules are not accommodated in the outer case 14, and therefore, when applied to such a thermoelectric conversion module, they may be used without being accommodated in the housing.

  As described above, according to the present embodiment, the thermoelectric conversion module 500 having various effects and having a joint structure with high joint reliability can be realized.

A second embodiment of the present invention will be described with reference to FIGS.
In the second embodiment, as shown in FIG. 6, the shape of the sample support 201 is different from the sample support jig 20 described in FIG. 2 in the first embodiment.

  FIG. 6 is a side view of the vicinity of an element extracted from an assembly process example of the electrodeless thermoelectric conversion element assembly 1 according to the second embodiment of the present invention. The same components as in Example 1 are assigned the same numbers as in Example 1. 1 is an electrodeless thermoelectric conversion element assembly, 11 is a p-type thermoelectric conversion element, 12 is an n-type thermoelectric conversion element (hereinafter, the p-type thermoelectric conversion element and the n-type thermoelectric conversion element are collectively referred to as a thermoelectric conversion element 100). , 15 and 16 are metal foils, 201 is a sample support jig, 22 is an upper bonding jig, 23 is a protrusion, and 24 is a groove. The metal foils 15 and 16 will be described as aluminum or an aluminum alloy foil containing silicon, germanium or the like in aluminum, or as a foil made of powder containing silicon, germanium or the like in aluminum or aluminum.

  The sample support jig 201 may be any material that does not melt in the joining process, such as ceramic or metal, but in the case of a material that reacts with the metal foils 15 and 16, the reaction is suppressed on the surface of the sample support jig 201. Or a layer that does not react, or a material (such as ceramic) that suppresses or does not react is interposed between the sample supporting jig 201 and the metal foils 15 and 16. Hereinafter, a flow chart of an assembling method of the electrodeless thermoelectric conversion module 1 of FIG. 6 will be described with reference to (a) to (d).

  First, as shown in FIG. 6A, the metal foil 15 is placed on the sample supporting jig 201 having the groove 24 (S601). The groove 24 is formed at least under any boundary except the boundary where the p-type thermoelectric conversion element 11 and the n-type thermoelectric conversion element 12 are joined. The thickness of the metal foil 15 is preferably 1 to 500 μm. After the metal foil 15 is installed, the thermoelectric conversion element 100 is aligned so that the groove 24 of the sample supporting jig 20 is positioned at least between the p-type thermoelectric conversion element 11 and the n-type thermoelectric conversion element 12 that are not joined. (S602) The thermoelectric conversion element 100 is placed on the sample support jig 201 so as to sandwich the metal foil 15 (S603). The thermoelectric conversion element 100 may be installed in a lump using a jig (not shown) or may be individually installed, and the method is not limited.

  Next, the metal foil 16 is placed on the thermoelectric conversion element 100 installed as shown in FIG. 6B (S604), and the upper joining jig 22 having the protrusions 23 is aligned (S605). The protrusion 23 of the upper joining jig 22 is formed at least under any boundary except the boundary where the p-type thermoelectric conversion element 11 and the n-type thermoelectric conversion element 12 are joined. It is desirable that the height of the protrusions 21 is at least half of the thickness of the metal foil 16. The thickness of the metal foil 16 is preferably 1 to 500 μm. After the alignment, the upper joining jig 22 is pressurized by setting the load applied to the thermoelectric conversion element 100 to 0.12 kPa or more across the metal thin film 16 (S606).

  Next, as shown in FIG. 6C, the sample supporting jig 201 and the upper joining jig 22 are heated by heating means (not shown) in a pressurized state (S607), and the metal foil 15 , 16 is raised to a melting temperature (660 ° C. in the case of aluminum) or higher to melt the metal foils 15, 16 exceeding the melting temperature (S608). At this time, since the molten metal foil 15 flows into the groove 24 on the sample supporting jig 201 side, the interface 212 between the p-type thermoelectric conversion element 11 and the n-type thermoelectric conversion element 12 facing each other in the groove is A material in which the metal foil 15 is melted flows into the interface 212 between the p-type thermoelectric conversion element 11 and the n-type thermoelectric conversion element 12 where the p-type thermoelectric conversion element 11 and the n-type thermoelectric element 12 are not joined. The conversion element 12 is joined.

  On the other hand, the protrusion 23 serves as a dike with respect to the molten metal foil 16, and the molten metal foil 16 flows into the interface 232 between the p-type thermoelectric conversion element 11 and the n-type thermoelectric conversion element 12 without the protrusion 23, Inter-element connection members 152 and 162 are formed to realize joining of both thermoelectric conversion elements. After a certain period of time has elapsed since the start of heating, heating of the sample support jig 201 and the upper bonding jig 22 is stopped (S609).

  After that, as shown in FIG. 6D, pressurization to the thermoelectric conversion element 100 by the upper bonding jig 22 is stopped and the upper bonding jig 22 is raised (S610). Is removed from the sample support jig 201 to form the electrodeless thermoelectric conversion element assembly 1 (S611). In the flow described with reference to FIG. 6, the process of joining the upper and lower metal foils 15 and 16 together is shown. However, after joining one of them in advance, the other may be joined.

Here, the pressure is set to 0.12 kPa or more to prevent the thermoelectric conversion element 100 from being tilted at the time of joining, the thermoelectric conversion element 100 and the sample supporting jig 20, and the thermoelectric conversion element 100 and the upper joining purpose. This is because the molten metal foils 15 and 16 are discharged from the interface of the jig 22 as much as possible, and the adhesion between the thermoelectric conversion element 100, the sample support jig 20, and the upper bonding jig 22 is enhanced. The upper limit of the applied pressure is not particularly limited, but is set to be less than the crushing strength of the element because it is necessary that the element is not destroyed. Specifically, it may be about 1000 MPa or less, but in the embodiment of the present invention, as described in Patent Documents 3 and 4, a pressure of 300 kg / cm ² or more and 700 kg / cm ² or less is applied at the time of joining, Even without applying a pressure of about several tens of MPa, a sufficient effect can be obtained with a pressure of about several MPa.

  The bonding atmosphere may be a non-oxidizing atmosphere. Specifically, a vacuum atmosphere, a nitrogen atmosphere, a nitrogen-hydrogen mixed atmosphere, or the like can be used. When the thermoelectric conversion element 100 is a silicon-germanium element and the metal foils 15 and 16 are aluminum, a layer containing aluminum, silicon, and germanium is formed at the bonding interface between the silicon-germanium element and aluminum. In this layer, a silicon-aluminum layer containing germanium and a silicon-germanium alloy layer containing aluminum of not more than 10% by mass formed by dissolving silicon-germanium constituting the thermoelectric conversion element 100 in aluminum. May be formed. In this case, the interface between the thermoelectric conversion element 100 and the molten metal foil has a structure composed of a plurality of alloy layers including an alloy layer containing silicon, germanium, and aluminum and an alloy layer mainly containing silicon and germanium.

  This alloy layer has high bonding strength and is excellent in oxidation resistance because it contains aluminum, and it is difficult for the bonded portion to deteriorate even in a high temperature environment in the atmosphere. In addition, an alloy containing aluminum, silicon, and germanium is relatively soft, and thus has an action of relieving stress generated at the joint. By these actions, the bonding layer in which an alloy containing aluminum, silicon, and germanium is formed exhibits high bonding reliability over a long period of time. The operation and effect of this bonding layer is as described above, and even if the bonding portion is formed as a multilayer as described above, it can be used without any problem. Note that the upper limit of the bonding temperature is a temperature at which the performance of the thermoelectric conversion element does not deteriorate, specifically, 1000 ° C. or less.

  In the above description, aluminum foil is used as the metal foils 15 and 16, but an aluminum alloy foil containing silicon, germanium or the like in aluminum may be used instead of the aluminum foil. In this case, since the component of the thermoelectric conversion element is contained in aluminum, a eutectic liquid phase is likely to be generated without solid phase diffusion. Further, an aluminum foil and an aluminum alloy foil may be laminated and used.

  Furthermore, instead of the metal foil, aluminum powder or aluminum alloy powder containing silicon, germanium or the like in aluminum may be used. In this case, you may use as a single powder, the layer formed from each powder may be laminated | stacked, and these mixed powders may be used. When such a powder is used, a compact formed by compacting only the powder may be disposed only at a location where the p-type thermoelectric conversion element 11 and the n-type thermoelectric conversion element 12 are joined, or the thermoelectric conversion element 100 in advance. The powder may be applied only to the place where the bonding is performed, and the powder paste formed using a resin or the like may be applied to the portion where the thermoelectric conversion element is bonded. Since the step of installing the foil can be omitted by applying the powder in advance, the manufacturing process can be further simplified.

  As the thermoelectric conversion element 100, other thermoelectric conversion elements such as a magnesium silicide thermoelectric conversion element and a manganese silicide thermoelectric conversion element can also be used. That is, each of these thermoelectric conversion elements contains silicon as a component, and can be joined by the above aluminum and silicon.

  Here, when a magnesium silicide thermoelectric conversion element is used as the thermoelectric conversion element 100, the bonding layer includes a layer structure including an alloy layer containing silicon, magnesium, and aluminum and an alloy layer containing silicon and magnesium as main components. can do.

  In order to obtain such a bonding layer, instead of the aluminum foil or aluminum powder of the above assembly method, an aluminum alloy foil containing silicon, magnesium or the like in aluminum or an aluminum alloy powder containing silicon, magnesium or the like in aluminum is used. It may be used. However, when a magnesium silicide thermoelectric conversion element is used as the thermoelectric conversion element 100, a eutectic phase is generated between aluminum and magnesium at 437 ° C., so the junction temperature is set to 440 ° C. or higher. Further, since magnesium is easily sublimated at a high temperature, the upper limit of the joining temperature is set to 800 ° C. in order to avoid sublimation of magnesium. Other assembly conditions are the same as those shown in FIG.

  In addition, when a manganese silicide thermoelectric conversion element is used as the thermoelectric conversion element 100, the obtained bonding layer has a layer structure including an alloy layer containing silicon, manganese, and aluminum and an alloy layer mainly containing silicon and manganese. It can be. In order to obtain such a bonding layer, instead of the aluminum foil or aluminum powder of the above production method, an aluminum alloy foil containing silicon, manganese or the like in aluminum or an aluminum alloy powder containing silicon, manganese or the like in aluminum is used. It may be used. Each manufacturing condition when a magnesium silicide thermoelectric conversion element is used as the thermoelectric conversion element is the same as that of the silicon-germanium thermoelectric conversion element.

  It is conceivable that, at the joint between the molten metal foils 15 and 16 and the thermoelectric conversion element 100, the reaction is promoted under a manufacturing process or an actual use environment depending on the volume of the metal foil. Therefore, you may form the diffusion prevention layer (reaction suppression layer) previously in the arbitrary locations of the thermoelectric conversion element 100 used as a joining interface. This diffusion prevention layer may be tungsten, titanium, nickel, palladium, molybdenum or the like. This diffusion prevention layer can be formed by plating, vapor deposition, sputtering, thermal spraying, aerosol deposition, or the like.

  When the assembly process according to this embodiment is used, in addition to the advantages of the assembly process according to the first embodiment, the sample support jig 201 according to this embodiment includes the sample support jig shown in FIG. 2 in the first embodiment. Since there is no projection 21 as formed on the jig 20, it is possible to avoid the risk of accidentally placing the thermoelectric conversion element 100 on the projection and damaging it during alignment. Since the electrodeless thermoelectric conversion element assembly 1 formed by the process of FIG. 6 has the same form as the electrodeless thermoelectric conversion element assembly 1 formed by the process of FIG. 2, the process is similar to that of FIGS. The thermoelectric conversion module 500 can be formed.

  FIG. 7 is a side view of the element vicinity of the thermoelectric conversion module 700 in the third embodiment of the present invention. Reference numeral 10 denotes a bonding material, 11 denotes a p-type thermoelectric conversion element, 12 denotes an n-type thermoelectric conversion element, and 14 denotes an outer case. The third embodiment has a structure in which the high thermal conductive insulating material 13 is eliminated from the thermoelectric conversion module 500 of the first embodiment shown in FIG. 3B, and the bonding material 10 is described in the first and second embodiments. Is the same as

  The bonding material 10 (161) on the upper surface side and the bonding material 10 (151) on the lower surface side may be the same material or different materials. The p-type thermoelectric conversion element 11 and the n-type thermoelectric conversion element 12 (hereinafter collectively referred to as the thermoelectric conversion element 100) can be selected from the same materials as those described in the first and second embodiments. it can.

  In the following examples, the p-type thermoelectric conversion element 11 is composed of silicon and germanium powder containing impurities such as boron, aluminum, gallium and the like that give the characteristics of a p-type semiconductor, and the n-type thermoelectric conversion element 12 is A silicon-germanium thermoelectric conversion element obtained by sintering silicon-germanium powder containing impurities of 1% or less, such as phosphorus and antimony, imparting the characteristics of an n-type semiconductor, respectively, by a pulse discharge method or a hot press method will be described.

  In the present embodiment, the material of the outer case 14 needs to be an insulating material in order to make direct contact with the p-type thermoelectric conversion element 11 and the n-type thermoelectric conversion element 12, and is mainly made of ceramic, carbon or the like. A material having high thermal conductivity as a component is desirable.

  In this embodiment, the bonding material 10 is described as aluminum or an aluminum alloy foil containing silicon, germanium or the like in aluminum, or a foil made of powder containing silicon, germanium or the like in aluminum or aluminum.

  As shown in FIG. 7, the p-type thermoelectric conversion element 11 and the n-type thermoelectric conversion element 12 are joined at the upper end and the lower end by a bonding material 10 to form the electrodeless thermoelectric conversion element assembly 1. Furthermore, the outer peripheral case 14 and the thermoelectric conversion element 100 are connected in contact with each other, and the shape is maintained by pressurizing the outer peripheral case 14 with screws or the like from the upper and lower surfaces, or by airtight sealing vacuum packaging.

  The thermoelectric conversion module 700 is a module that generates an electromotive force according to the temperature difference by giving a temperature difference to both ends of the thermoelectric conversion element 100. The case where the upper surface of FIG. 7 is made high and the lower surface is made low is shown below.

  A current flows through the thermoelectric conversion element 100 due to the temperature difference applied to the upper and lower surfaces. The current flows from the high temperature side to the low temperature side (in FIG. 7, from top to bottom) in the p-type thermoelectric conversion element 11, and from the low temperature side to the high temperature side (in FIG. 7, from bottom to top) in the n-type thermoelectric conversion element 12. A series path is formed by joining the downstream side of each thermoelectric conversion element 100 to the upstream side of the adjacent thermoelectric conversion element 100 using the bonding material 10. The electrodeless thermoelectric conversion element assembly 1 is configured by joining a plurality of thermoelectric conversion elements 100 connected in series as described above in a planar shape or on a line.

  If the electrodeless thermoelectric conversion element assembly 1 and the outer case 14 are joined when the high temperature side becomes 300 ° C. or higher in an actual use environment, stress and strain are generated near the joint due to the difference in linear expansion coefficient between the element and the case. There is concern about the occurrence of breakage and peeling of the joint portion and cracking of the thermoelectric conversion element 100 constituting the electrodeless thermoelectric conversion element assembly 1. However, in this structure, since the electrodeless thermoelectric conversion element assembly 1 and the outer peripheral case 14 are in contact connection, stress and strain can be reduced by slipping the interface. Moreover, it can be expected that the thermal resistance is reduced by the direct thermal propagation of the thermoelectric conversion elements 100 constituting the outer case 14 and the electrodeless thermoelectric conversion element assembly 1.

  Furthermore, since the electrodes used in Patent Document 5 are eliminated, the ratio of the thermoelectric conversion elements 100 per unit area in the planar direction can be increased, and the mounting density of the thermoelectric conversion elements is increased, so the power generation amount per unit area is increased. To increase. That is, space-saving power generation is possible.

  DESCRIPTION OF SYMBOLS 1 ... Electrode-less thermoelectric conversion element assembly 10 ... Bonding material 11 ... p-type thermoelectric conversion element 12 ... n-type thermoelectric conversion element 13 ... High heat conductive insulating material 14 ... Outer case 15, 16 ... Metal foil 20 ... Jig for sample support DESCRIPTION OF SYMBOLS 21, 23 ... Protrusion 22 ... Upper joining jig 24 ... Groove 30 ... Lower outer case 32 ... Upper outer case 31, 33 ... High thermal conductive insulating material 100 ... Thermoelectric conversion element 500,700 ... Thermoelectric conversion module.

Claims (4)

A method for manufacturing a thermoelectric conversion module, comprising:
A plurality of p-type thermoelectric conversion elements containing silicon and a plurality of n-type thermoelectric conversion elements containing silicon are alternately arranged with the high-temperature side surface and the low-temperature side surface aligned,
The bonding metal material and the bonding metal material having aluminum as a main component sandwiched between bonding portions between the plurality of p-type thermoelectric conversion elements and the plurality of n-type thermoelectric conversion elements arranged alternately. A component of the thermoelectric conversion element including silicon is contained in the aluminum between the p-type thermoelectric conversion element and between the bonding metal material and the n-type thermoelectric conversion element, and is generated at the junction. A plurality of the p-type thermoelectric conversion elements and the plurality of n-type thermoelectric conversion elements are connected in series in a state where a plurality of alloy layers having an action of relaxing stress are formed,
The high-temperature-side surfaces and the low-temperature-side surfaces of the plurality of p-type thermoelectric conversion elements and the plurality of n-type thermoelectric conversion elements that are electrically connected in series are insulating materials having good thermal conductivity. A method of manufacturing a thermoelectric conversion module, characterized by covering. 2. The method of manufacturing a thermoelectric conversion module according to claim 1 , wherein the insulating material having good thermal conductivity is attached to a metal case, and the plurality of p-type thermoelectric conversion elements and the plurality of n-type thermoelectric conversions. Covering the surface on the high temperature side and the surface on the low temperature side of the element with the insulating material with good thermal conductivity is covering with the insulating material with good thermal conductivity attached to the metal case, The high temperature side surface and the low temperature side surface of the plurality of p-type thermoelectric conversion elements and the plurality of n-type thermoelectric conversion elements are connected to the insulating material having good thermal conductivity by contact. The manufacturing method of the thermoelectric conversion module characterized by the above-mentioned. 2. The method of manufacturing a thermoelectric conversion module according to claim 1 , wherein the p-type thermoelectric conversion element and the n-type thermoelectric conversion element are electrically connected in series by heating aluminum or an aluminum alloy. A method of manufacturing a thermoelectric conversion module, wherein a plurality of alloy layers are formed between the p-type thermoelectric conversion element and the n-type thermoelectric conversion element and electrically connected to each other. 2. The method of manufacturing a thermoelectric conversion module according to claim 1 , wherein the bonding metal material includes a plurality of the p-type thermoelectric conversion elements and a plurality of the n-type thermoelectric conversion elements on the high temperature side surface and the low temperature. A method for producing a thermoelectric conversion module, comprising: forming a metal foil on a side surface and heating and melting the metal foil.

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